The invention relates to a tubular foodstuff casing, in particular a synthetic sausage casing, made of cellulose hydrate and having a coating on its outside, which contains a fungicide.
The difficulty with foodstuff casings made of cellulose hydrate is that during storage before being filled with the foodstuff they are infested by undesired mold and other microorganisms, and thus become useless. The growth of the mold is particularly accelerated if the foodstuff casings, before being processed, are stored with a relatively high humidity content, which is required to guarantee sufficient flexibility of the casing.
To prevent this disadvantageous effect, it is known to apply glycerol monolaurate as a fungicide on the external surface of cellulose tubes (EP-A0,141,066, equivalent to U.S. Pat. No. 4,662,403). Compared with water-soluble fungicidal compounds, this compound has the advantage of still being present in a sufficient amount on the external surface even after the casing has been processed, in particular even after the hot water treatment of the sausage casing stuffed with the sausage meat. This fungicide is also used to protect sausages, which are enclosed in a secondary packaging, for example in a plastic bag, and have a sausage skin made of cellulose, from the undesired infestation of the cellulose layer by mold.
In a further development of this known coating, the outer coating additionally contains, apart from glycerol monolaurate, potassium sorbate which is bound to the surface of the sausage casing made of fiber-reinforced cellulose by means of crosslinked protein (casein/glyoxal) (DE-A 36 06 195, equivalent to U.S. Pat. No. 4,666,750). This coating has the additional function of preventing the degradation of cellulose by cellulolytic enzymes.
In another published alternative, the potassium sorbate is anchored to the tube surface with epichlorohydrin/polyamine/polyamide resin and is preferably present on the tube inner surface, while glycerol monolaurate is present on the tube outer surface (EP-A 0,247,437). According to the teaching of this publication, premoistened sausage casings made of fiber-reinforced cellulose, which are processable without further watering, are intended to be protected against infestation by mold.
It is true that these known formulations still have sufficient action after simmering or boiling of the tubular casings filled with pasty foodstuffs. However, it was found that in the case of long-lasting and intensive action of mold spores even these agents do not give sufficiently safe protection against infestation of the cellulose casing by mold. If, for example, long-keeping sausages are dried in the air for several weeks next to those types of salami which on their outer surfaces are populated by noble mold, the long-keeping sausage casings grow molds in the course of time caused by the constant action of the mold spores emanating from the types of salami, even if they have been treated with one of the above-mentioned fungicidal external coatings. Even sausages packaged into plastic bags are highly susceptible to infestation by mold spores under unfavorable conditions of storage (high temperature and humidity) so that the action of the known fungicides may not be sufficient under certain circumstances.
In accordance with German application P 38 07 070.7, not pre-published, corresponding to U.S. Pat. No. 4,940,615, heterocyclic compounds, in particular benzimidazole and isothiazolone compounds, such as N-alkyl-isothiazolone, are applied to the outer surface of the sausage casings as fungicides.